The invention relates to a sheet-processing apparatus for depositing sheets, in particular banknotes, in stacks, and also relates to a process for setting up such a sheet-processing apparatus.
The invention will be explained hereinbelow specifically using the example of a banknote-processing apparatus, but it goes without saying that it is also possible for other xe2x80x9csheetsxe2x80x9d to be processed by the sheet-processing apparatus.
Banknotes occurring in relatively large quantities can be processed by known sheet-processing apparatuses such that damaged and/or worn banknotes are separated from banknotes in good condition and are deposited in different depositing compartments. It is also possible for banknotes of different formats and/or denominations to be sorted and deposited as stacks in different compartments.
Known sheet-processing apparatuses usually contain a separator which separates banknotes from a stack of banknotes of different qualities (banknotes in good condition and those in poor condition, banknotes of different formats, etc.), transfers the separated banknotes to a transporting unit and, with the aid of a sensor device, checks quality features in order to form depositing criteria, whereupon the banknotes are transported from the transporting unit to different depositing compartments, in dependence in each case on the depositing criteria determined. Each depositing compartment is assigned a stacker wheel. A stacker wheel contains stacker fingers which run helically on a disk-like or roller-like carrier, the wheel being driven in a direction which is counter to the orientation of the stacker-finger tips.
The separated banknotes, which are being processed in respect of their selection criteria by the sensor device and are directed to one of the plurality of stacker wheels in accordance with the selection criteria, are directed into a sheet compartment which is formed between in each case two adjacent stacker fingers. The individual stacker fingers have a smaller width than the banknotes and have their outer ends running through a stop wall of a depositing compartment. The banknotes located in the individual sheet compartments are moved towards the base of the depositing compartment by the rotation of the stacker wheel, while the leading edge of the banknote, directed toward the center of the stacker wheel, is retained against the stop wall of the depositing compartment and moved along said wall in the direction of the base of the depositing compartment.
Such sheet-processing apparatuses with the individual components are known. You are referred, for example, to DE 29 02 068 C2, which discloses a separator. A typical feature for a separator is a stack of sheets (stack of banknotes) which is moved against a retaining rack, in the vicinity of which is located a separator wheel, certain locations of which are subjected to negative pressure. The rotational speed of said separator wheel determines the frequency at which individual banknotes are discharged by the separator.
In order that the sheet-processing apparatus operates properly and the individual sheets (banknotes) are deposited correctly in the individual depositing compartments, each sheet compartment in each stacker wheel should only accommodate a single sheet. For this reason, the rotational speed (excluding in phase position) of the individual stacker wheels is set such thatxe2x80x94in dependence on the frequency at which the separator discharges the banknotesxe2x80x94not more than one banknote passages into a sheet compartment. The rotational speed of the stacker wheels is expediently set such that, on average, more than one sheet compartment is available for one banknote in each case.
In the case of the known sheet-processing apparatus, although the abovementioned setting of the rotational speed of the individual stacker wheels achieves a situation where no more than one banknote should pass into a sheet compartment of the stacker wheel, it may nevertheless be the case that a banknote strikes against a stacker-finger tip by way of its leading border. In the worst-case scenario, the banknote is slung out of the apparatus and possibly prevents other banknotes from being deposited. It is at least the case, however, that the banknotes coming into contact with the tip of a stacker finger are braked in an undefined manner and, accordingly, are not deposited correctly. Banknotes which pass into two sheet compartments, that is to say pass into the helical wheel obliquely in front of and behind the associated stacker-finger tips, may likewise affect the operation of other banknotes being deposited.
In the case of relatively small sheet-processing apparatuses, such as counting machines, which have a separator, a transporting unit, sensors and one or more depositing compartments, the separator is frequently designed as a friction-wheel separator. In addition, it is possible for the housing and/or the transporting unit to be opened, for example for eliminating jams. This results in further problems when banknotes are deposited in the depositing compartments.
The object of the invention is to specify a sheet-processing apparatus of the type described above which ensures that the individual sheets are accommodated correctly in a sheet compartment of a stacker wheel and, accordingly, are deposited neatly.
It is also intended to specify a process which is intended for setting up a sheet-processing apparatus of the type described above and which guarantees that the sheet-processing apparatus operates properly, that is to say that the individual sheets are deposited correctly at all times.
This object is achieved according to the invention in that the rotational speed of the stacker wheels is synchronized with the frequency of the sheets discharged by the separator, to be precise such that each sheet entering into the sheet compartment of the stacker wheel passes approximately centrally through the opening between two adjacent stacker-finger tips. The phrases xe2x80x9cthe sheet passes centrally through the opening of the sheet compartmentxe2x80x9d, xe2x80x9cthe sheet enters approximately centrally between two stacker-finger tips of a sheet compartmentxe2x80x9d and the like, in the present context, mean that the sheet running into a sheet compartment is spaced apart, by way of its leading edge, to a sufficient extent both from the tip of the preceding stacker finger and from the tip of the following stacker finger, that is to say cannot in any case collide with the tip of a stacker finger. In the invention, the use of a common drive motor, with rigid mechanical coupling, would force the separator and the stacker wheels to run synchronously. Nevertheless, in order to achieve in-phase synchronization, that is to say in order for each sheet to run centrally into a sheet compartment of the stacker wheel, it is necessary to set the position of the separator wheel relative to the position of the stacker wheels. For this purpose, in the case of the common drive motor, a clutch is then arranged, in conjunction with a brake, between said drive motor and the separator. Before the beginning of the stacking operation, the drive motor is set in motion until the separator reaches a previously defined synchronizing position. The separator is then uncoupled from the common drive motor. The brake keeps the separator in the defined synchronization position. The stacker wheels (together with the sheet-transporting means) are then rotated further by the drive motor until they too have reached the previously defined synchronizing position, that is to say until the synchronization-signal transmitter assigned to the stacker wheels supplies the synchronizing pulse. At that moment, the force fit between the common drive motor and the separator is re-established, with the result that the separator and stacker wheels then rotate synchronously in phase.
The above initializing sequence can be carried out before the sheet-processing apparatus is brought into operation in each case, but at least following each instance of intervention in the machine, for example following each cleaning operation or following each time a sheet jam is eliminated, etc. If it proves to be the case in a check during operation that, on account of signs of a drift, the individual sheets arrive at a relatively large distance from the center of the sheet-compartment opening, then it is possible for the machine to be stopped and for an initializing sequence to be introduced.
The synchronization between the separator, on the one hand, and the stacker wheels (and the transporting means located therebetween), on the other hand, implies that the stacker wheels are synchronized with one another. This can expediently be achieved mechanically with the aid of one or more toothed belts, by means of which in each case at least two stacker wheels are coupled. Seated on the axes of rotation of the stacker wheels are gearwheels, around which the associated toothed belt is wound. In the sheet-processing apparatus, the sheets (banknotes) fed to the different stacker wheels and depositing compartments, following their distribution in dependence on the depositing criteria determined, cover transporting paths which are possibly of different lengths. For this reason, the stacker wheels are also set with different xe2x80x9cphase positionsxe2x80x9d, namely such that the sheet arriving sooner or later at the respective stacker wheel in dependence on the length of the transporting path passes into the center of a sheet-compartment opening.
A particularly straightforward arrangement with fixed synchronization is achieved when the gearwheel for the toothed belt, which is assigned to a respective stacker wheel, is provided with a number of teeth which corresponds to the number of sheet compartments. The setting of the stacker wheels on their axes of rotation in relation to the setting of the rest of the stacker wheels takes place a single time in the necessary phase position in dependence on the individual transporting-path length. If, on a stacker wheel, the associated gearwheel has the same number of teeth as the stacker wheel has sheet compartments, it is even possible, during later operation, for the toothed belt to jump by one or more teeth without adversely affecting the synchronization of the stacker wheels in relation to one another.
As far as the synchronization between the separator, on the one hand, and the stacker wheels, on the other hand, is concerned, in each case one synchronization-signal transmitter is expediently assigned to the separator, on the one hand, and all the stacker wheels, on the other hand. Such a signal transmitter is, for example, in the form of a Hall sensor in conjunction with a magnet arranged on the revolving wheel of the separator and/or a magnet arranged on a stacker wheel, with the result that, in the case of defined positions of the relevant wheels, the associated Hall sensor supplies a pulse signal as a synchronization signal. The electronic control means of the apparatus can then carry out the synchronization according to the invention between the separator and stacking wheels with the aid of said synchronization signals.
Depending on the type of machine, the stacker wheels, on the one hand, and the separator, on the other hand, each have a dedicated drive motor or they have a common drive motor.
The constant monitoring and readjustment for maintaining optimized synchronization between the separator and stacker wheels can also be carried out if the separator and the stacker wheels each have a separate drive motor. Dispensing with the coupling and braking arrangement for the separator, both the separator and the group of stacker wheels each supply a synchronization signal to a control device, the control device then initially allowing an initializing sequence, which is similar to the abovedescribed initializing sequence, to proceed. During operation, it is then also possible for the control device, with the aid of the synchronization signals, to detect a possible increasing phase deviation between the synchronization signals and to readjust the same correspondingly.
The operation of properly depositing the individual sheets or banknotes is possibly also adversely affected in the prior art by a sheet located in one sheet compartment of the stacker wheel colliding with a sheet located in an adjacent sheet compartment. If, for example, a banknote is dog-eared or has tears, parts of the banknote project out of the xe2x80x9cplanexe2x80x9d of the banknote, which possibly constitutes an obstruction for a banknote moving in the vicinity. In order to avoid individual banknotes being obstructed in this way by adjacent, damaged banknotes, the invention provides, in an independently protected configuration for a stacker wheel, that the stacker fingers of the latter have a defined minimum thickness, which guarantees a minimum spacing between parts of a sheet in one sheet compartment and a sheet located in an adjacent sheet compartment. The stacker fingers may preferably be of double-walled design, with the result that, despite the increased minimum thickness, they only have a low weight.
The thickened individual stacker fingers guarantee a minimum spacing between adjacent sheets in the stacker wheel, with the result that dog-ears or tears in one sheet do not constitute an obstruction for an adjacent sheet.
The synchronization according to the invention of the separator and the stacker wheels can be achieved with the aid of the hardware measures discussed in more detail above.
The synchronization according to the invention is achieved by a process according to the invention which, in the case of sheet-processing apparatuses, can be achieved by appropriate programming, provided that such a sheet-processing apparatus has means for synchronizing the plurality of stacker wheels with one another and for receiving synchronization signals in the stacker wheels, on the one hand, and from the separator, on the other hand. The process according to the invention provides the following steps: prior to operation, an initializing routine is carried out, this involving the separator and the synchronously running stacker wheels being synchronized with one another such that each sheet running into one of the sheet compartments has its leading edge running through the opening of the sheet compartment approximately centrally between the tips of the stacker fingers. For this purpose, in detail, the following steps are carried out:
the separator is moved into a defined synchronizing position and stopped there;
the stacker wheels are then moved into a defined synchronizing position (and possibly stopped there), and
from the respective synchronizing positions, the separator and the stacker wheels are then accelerated to the operating speed for the stacking operation.